In each of Problems 9-12, a vertical cross section of a tank is shown. Assume that the tank is 10 feet long and full of water, and that the water is to be pumped to a height 5 feet above the top of the tank. Find the work done in emptying the tank. 9. 11. -4 ft- 10. 3 ft 5 ft -4 ft- 12. 6ft- 6 ft- 3 ft - 4 ft